/**
 * @description: base64 to blob
 */
export function dataURLtoBlob(base64Buf) {
    const arr = base64Buf.split(',');
    const typeItem = arr[0];
    const mime = typeItem.match(/:(.*?);/)[1];
    const bstr = window.atob(arr[1]);
    let n = bstr.length;
    const u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
}

/**
 * img url to base64
 * @param url
 */
export function urlToBase64(url, mineType) {
    return new Promise((resolve, reject) => {
        let canvas = document.createElement('CANVAS');
        const ctx = canvas.getContext('2d');

        const img = new Image();
        img.crossOrigin = '';
        img.onload = function () {
            if (!canvas || !ctx) {
                return reject();
            }
            canvas.height = img.height;
            canvas.width = img.width;
            ctx.drawImage(img, 0, 0);
            const dataURL = canvas.toDataURL(mineType || 'image/png');
            canvas = null;
            resolve(dataURL);
        };
        img.src = url;
    });
}

export function downloadByOnlineUrl(url, filename, mime, bom) {
    urlToBase64(url).then((base64) => {
        downloadByBase64(base64, filename, mime, bom);
    });
}
export function downloadByBase64(buf, filename, mime, bom) {
    const base64Buf = dataURLtoBlob(buf);
    downloadByData(base64Buf, filename, mime, bom);
}

export function downloadByData(data, filename, mime, bom) {
    const blobData = typeof bom !== 'undefined' ? [bom, data] : [data];
    const blob = new Blob(blobData, { type: mime || 'application/octet-stream' });

    const blobURL = window.URL.createObjectURL(blob);
    const tempLink = document.createElement('a');
    tempLink.style.display = 'none';
    tempLink.href = blobURL;
    tempLink.setAttribute('download', filename);
    if (typeof tempLink.download === 'undefined') {
        tempLink.setAttribute('target', '_blank');
    }
    document.body.appendChild(tempLink);
    tempLink.click();
    document.body.removeChild(tempLink);
    window.URL.revokeObjectURL(blobURL);
}

/**
 * Download file according to file address
 * @param {*} sUrl
 */
export function downloadByUrl(url, target = '_blank', fileName) {
    const isChrome = window.navigator.userAgent.toLowerCase().indexOf('chrome') > -1;
    const isSafari = window.navigator.userAgent.toLowerCase().indexOf('safari') > -1;

    if (/(iP)/g.test(window.navigator.userAgent)) {
        console.error('Your browser does not support download!');
        return false;
    }
    if (isChrome || isSafari) {
        const link = document.createElement('a');
        link.href = url;
        link.target = target;

        if (link.download !== undefined) {
            link.download = fileName || url.substring(url.lastIndexOf('/') + 1, url.length);
        }

        if (document.createEvent) {
            const e = document.createEvent('MouseEvents');
            e.initEvent('click', true, true);
            link.dispatchEvent(e);
            return true;
        }
    }
    if (url.indexOf('?') === -1) {
        url += '?download';
    }

    openWindow(url, { target });
    return true;
}
